1. Field of the Invention
The present invention relates to a ball chair, and more particularly to a ball chair having a retaining device to hold a spherical cushion on a seat in position to enhance the safety of the ball chair.
2. Description of Related Art
A conventional ball chair is composed of a chair and a spherical cushion. The chair has a seat frame with a top face and a partly-spherical passage defined in the top face of the seat frame to receive a lower portion of the spherical cushion inside. By placing the spherical cushion in the partly-spherical passage of the chair, a ball chair is achieved. However, when a user sits on the ball chair, the spherical cushion is deformed forward and falls out of the partly-spherical passage such that the user easily falls from the ball chair. Additionally, when the ball chair is bumped or vibrated, the spherical cushion rebounds and easily springs out of the partly-spherical passage. Therefore, the ball chair is neither safe nor stable for the user.
The present invention has arisen to mitigate or obviate the disadvantages of the conventional ball chair.